Cargo tank support



NOV. 28, 1967 Y 56 3,355,135

CARGO TANK SUPPORT Filed Jan. 15, 1966 United States Patent 3 Claims.(Cl. 248-350) ABSTRACT OF THE DISCLOSURE A support for a cargo tanksubjected to thermal movements, e.g. for transporting cryogenic gases,consists of members having different height in unloaded condition, thetaller of said members being widely spaced and designed alone to carrythe container in empty condition and to permit a limited sidewardmovement of the container bottom in relation to the support base,whereas the shorter members are located some distance from the tall onesand disposed in such a manner that the bottom of the tank during loadingand simultaneous cooling will reduce its size before it is lowered downonto the shorter members.

The present invention relates to cargo ship structures and is concernedwith the provision of novel means for supporting a container subjectedto thermal movements, especially a cargo tank in a ship. Resilientsupport means are necessary when the temperature of the cargo differsmaterially from that of the ambient temperature. This is the case, forinstance, when condensed gases are transported at atmospheric pressure,but the invention may also be utilized for containers adapted to carryheated cargo.

In designing such supports the following (amongst other) demands must bemet:

(a) thermal movements of the container mitted to take place;

(b) the considerable weight of the filled container must be transferredto the support base;

(c) the support members must be as poor conductors of heat as possible;

(d) the container must retain frictional contact with the base.

Hitherto known proposals take some but not all of these points intoconsideration simultaneously and, thus, are compromises only.

One object of the present invention is to design a support meansfulfilling all demands above stated, and which at the same time iseconomically favorable due to its simple construction.

A further object of the invention is to design the support means whosesupport members are not directly influenced by the low temperatureprevailing in the container.

The design is based on the consideration that the temperature of thecontainer initially is slowly brought down to the working temperature bythe introduction of small quantities of the cargo (condensed gas), insuch a manner that the contraction (or, reversely, the expansion) ismainly completed before the main loading takes place. By having thecontainer resting on a few support members only during the contraction(or, expansion) period, which support members are designed to permit alimited movement between the container and the support base, it ispossible to take care of thermal movements in all directions withoutundue stresses occurring. During the ensuing loading of the container areduction of the height of the supports will take place in such a mannerthat must be percertain parts of the container bottom structure (or, ofsupport members fitted thereto) will support the container.

The invention is illustrated by way of example in the attached drawing,in which:

FIGS. 1-3 inclusive schematically show a container according to theinvention in three different loading positions-first empty, thereaftercarrying an insignificant portion of cargo only, and finally practicallyfilled;

FIG. 4 is a side View, on a larger scale, of the support arrangementaccording to the invention;

FIG. 5 is a section along line VV in FIG. 4; and

FIG. 6 illustrates a modification of the support member shown in FIG. 5.

In FIGS. 1-3 inclusive a container is denoted by 1, and a support basefor the same is denoted by 2. This support base forms part of aconstruction, for instance the cargo hold of a ship, enclosing thecontainer 1. Primary support members according to the invention areindicated by 3 and between these are arranged further relief supports 4,designed as shims or the like. Means for fixing the center of the bottomof the container 1 in relation to the support base 2 withouttransferring any vertical load are indicated by 5.

FIG. 1 shows the container 1 at normal temperature and Without anycargo. The support members 3 are designed in such a manner that theywill then carry the container with the lower surfaces of relief supports4 free from the base 2.

In FIG. 2 a small amount of cargo-for instance cool, condensed gashasbeen introduced into the container 1, which due to the low temperatureof the cargo will contract from the position indicated by dash-dottedlines to the position 1' shown in full lines. This position will mainlycorrespond to the maximum contraction caused by the cargo in question.It will be noted that the amount of cargo introduced for this purpose isinsufiicient to depress the container to such a degree that the reliefsupport surfaces fitted to the bottom of the container contact thesupport base.

In FIG. 3 the container is practically filled with cargo and its wallsare disposed in position 1 shown. Due to the weight of the cargo thesupport members 3 have now been compressed in such a manner that thedistance between the container bottom and the base is reduced: therelief support surfaces 4 now carry the whole or an essential part ofthe weight of the container and cargo.

An embodiment of the invention wherein the demands for highly eficientinsulation below the container is met is shown in detail in FIGS. 4 and5. Distance blocks 6 of insulating material, for instance slabs of woodglued together, are fitted to the bottom of the container and betweenthe sides of these blocks insulation material, not shown, is arranged.These distance blocks are permanently fixed to the bottom structure ofthe container and the support members 3 are fitted to the underside ofthe blocks. In this embodiment the support members consist of aresilient material, for instance rubber or synthetic resin, and arepreferably glued to the underside of the blocks and to channel-shapedmountings 7 at the support base 2. The location at the underside of theinsulating blocks protects the support members from the low temperatureprevailing in the container and the material thereof retains itsresilient properties.

The underside of the blocks, may, between the places where the primarysupports are fitted, to be shaped in different ways depending on themagnitude of the movements which may be expected between them and thesupport base. In blocks arranged close to the center of the container itmay, for instance, be suitable to design the relief support surfaces 4as parts 8 of the distance blocks 6 proper (right part of FIGURE 5).Towards the periphcry of the container bottom the movements betweencontainer and support may be considerable. If, furthermore, the supportbase forms part of a longitudinal strength member of a ship it will besubjected to alternating hogging and sagging movements when the shipmoves through the waves. In these cases the relief supports 4 mayconsist of slabs 9 of rubber or synthetic resin fitted to the blocks inappropriate places. These slabs are, however, thinner than thefirst-mentioned type of support members, 3, and are made from a materialwhich is considerably less compressible than is the material in members3.

The support members 3 are made from such a compressible material and aredesigned in such a manner that lateral movement of the container inrelation to the base may occur. The material in the support members 3 isadapted to be elastically deformed, and will, for a certain amount ofload, be compressed sufficiently to bring the surfaces of reliefsupports 4 into action. The required amount of load for this purpose maybe chosen according to circumstances. Usually a certain amount of cargois left in the tank, when this is unloaded, to keep the temperature ofthe tank low and possibly also to serve as fuel during the returnvoyage. It is recommended that the amount of retained cargo besuflicient to keep the container in its lower condition, even after theconsumption during the voyage.

FIG. 6 shows a modification of the support members 3 which here aredesigned as prismatic blocks, links or the like, 10, of non-compressiblematerial, for instance wood, steel or the like. These members 10 aremounted on pivots 11 carried by pairs of brackets 12 connected to thecontainer bottom 1 and to the support base 2, respectively, and areprovided with rounded upper and lower contact surfaces in such a mannerthat a reduction of the height is brought about by a relative movementbetween container and support base.

I claim:

1. Means for supporting a container subjected to thermal movements,especially a cargo tank in a ship, in relation to a support base bymeans of members having different heights in unloaded condition;comprising:

a plurality of a first type of widely spaced relatively tall supportmembers attached to the container bottom structure as well as to thesupport base, said first type support members being designed alone tocarry the empty container at a distance from the support base and topermit a limited movement of the container in relation to said supportbase;

a plurality of a second type relatively short support members beingfixed to either the bottom structure of said container or to the basesupport at a distance from said first support members, whereby during aninitial decrease in temperature of the container a relative movementbetween said container and the support base may take place beforesupport members of said second type become engaged for carryingpurposes.

2. Supporting means according to claim 1, characterized in that saidfirst type of support members are formed of a resilient rubber-likematerial.

3. Supporting means for supporting a container subjected to thermalmovements, especially a cargo tank in a ship, in relation to a supportbase by means of members permitting a limited movement of the containerin relation to said support base, comprising: a plurality of a firsttype of widely spaced support members attached to the container bottomstructure as well as to the support base, said first type supportmembers serving to carry the empty container at a distance from thesupport base; and a plurality of a second type support members theheight of which is less than that of said first members when said firstsupport members are unloaded; said second type of support members beingfixed to either the bottom structure of said container or to the basesupport and located in such relation to said first support members thatduring an initial decrease in temperature of the container a relativemovement between said container and the support base may take placewithout the second type of support members being engaged, whereas duringcontinued loading of the container said first type of support membersare displaced sufficiently to reduce the distance between the bottom ofthe container and the support base such that the container in loadedcondition is carried by both of said two types of support members andwherein said first type of support members consist of prismatic linksformed of a non-compressible material and having rounded upper and lowercontact surfaces and being pivotally connected to the container bottomstructure and to the supporting base, respectively.

References Cited UNITED STATES PATENTS 3,026,577 3/1962 Dosker 114-74 XFOREIGN PATENTS 134,150 7/1933 Austria.

RAY D. FRAZIER, Primary Examiner.

CHANCELLOR E. HARRIS, Examiner.

F. DOMOTOR, Assistant Examiner.

1. MEANS FOR SUPPORTING A CONTAINER SUBJECTED TO THERMAL MOVEMENT,ESPECIALLY A CARGO TANK IN A SHIP, IN RELATION TO A SUPPORT BASE BYMEANS OF MEMBERS HAVING DIFFERENT HEIGHTS IN UNLOADED CONDITION;COMPRISING: A PLURALITY OF TYPE OF WIDELY SPACED RELATIVELY TALL SUPPORTMEMBERS ATTACHED TO THE CONTAINER BOTTOM STRUCTURE AS WELL AS TO THESUPPORT BASE, SAID FIRST TYPE SUPPORT MEMBERS BEING DESIGNED ALONE TOCARRY THE EMPTY CONTAINER AT A DISTANCE FROM THE SUPPORT BASE AND TOPERMIT A LIMITED MOVEMENT OF THE CONTAINER IN RELATION TO SAID SUPPORTBASE;